The present invention relates to irrigation equipment, and more particularly, to sprinklers of the type that use internal turbines to rotate a nozzle to distribute water over turf or other landscaping.
Many regions of the world have inadequate rainfall to support lawns, gardens and other landscaping during dry periods. Sprinklers are commonly used to distribute water over such landscaping in commercial and residential environments. The water is supplied under pressure from municipal sources, wells and storage reservoirs.
So called xe2x80x9chose endxe2x80x9d sprinklers were at one time in widespread use. As the name implies, they are devices connected to the end of a garden hose for ejecting water in a spray pattern over a lawn or garden. Fixed spray head sprinklers which are connected to an underground network of pipes have come into widespread use for watering smaller areas.
Impact drive sprinklers have been used to water landscaping over larger areas starting decades ago. They are mounted to the top of a fixed vertical pipe or riser and have a spring biased arm that oscillates about a vertical axis as a result of one end intercepting a stream of water ejected from a nozzle. The resultant torque causes the nozzle to gradually move over an adjustable arc and a reversing mechanism causes the nozzle to retrace the arc in a repetitive manner.
Rotor type sprinklers pioneered by Edwin J. Hunter of hunter Industries, Inc. have largely supplanted impact drive sprinklers, particularly on golf courses and playing fields. Rotor type sprinklers are quieter, more reliable and distribute a more precise amount of precipitation more uniformly over a more accurately maintained sector size.
A rotor type sprinkler typically employs an extensible riser which pops up out of a fixed outer housing when water pressure is applied. The riser has a nozzle in a rotating head mounted at the upper end of the riser. The riser incorporates a turbine which drives the rotating head via a gear train reduction, reversing mechanism and arc adjustment mechanism. The turbine is typically located in the lower part of the riser and rotates about a vertical axis at relatively high spend. Some rotor type sprinklers have an arc return mechanism so that if a vandal twists the riser outside of its arc limits, it will resume oscillation between the arc limits to prevent sidewalks, people and buildings from being watered. Rotor type sprinklers used on golf courses sometimes include an ON/OFF diaphragm valve in the base thereof which is pneumatically or electrically controlled.
Reversing mechanisms in rotor type sprinklers have generally been complex arrangements. See for example U.S. Pat. No. 4,625,914 of Sexton et al. which discloses the use of a swirl plate that is shifted to align different ports so that water jets will reverse a ball drive. More typical is the reversing mechanism disclosed in U.S. Pat. No. 3,107,056 of Hunter in which a drive train includes a shifting mechanism that alternately shifts a pair of terminal gears carried on a shifting plate into and out of engagement with an internal gear at the ends of an oscillating stroke. U.S. Pat. No. 4,568,024 of Hunter discloses a more compact design for higher pop up stroke, higher volume rotor type sprinklers in which alternate driving pinion gears are shifted into driving engagement with an internal ring gear with the pressure angle of the engaging teeth being different for the different driving pinion gears to thereby balance the shifting force applied by a shifting mechanism. See also U.S. Pat. No. 4,718,605 of Hunter.
Reversing mechanisms for rotor type sprinklers need to have a mechanism to shift the gear train or stator of the reversing mechanism. Existing designs require multiple springs to secure the reversing mechanism in its reversed position until the next arc limit is reached and to provide a spring force to allow ratcheting or clutching for arc setting or vandal protection. A xe2x80x9cdead spotxe2x80x9d is often present about a central axis where the forces of all of the springs line up such that the reversing mechanism can stall and not complete shifting to its opposite state. The rotor type sprinkler thus malfunctions because the stream of water no longer moves across the prescribed arc but is frozen in a stationary position.
The aforementioned U.S. Pat. No. 4,718,605 of Hunter discloses a reversing mechanism for a rotor type sprinkler which includes a lost motion connection between a shifting arm and a shiftable carrier. The carrier has a pair of driving pinions. Separate over-center spring units bias the carrier and the shifting arm to alternate driving engagement positions. While this arrangement has been successfully commercialized on a widespread basis, it would be desirable to provide a simpler, more reliable over-center mechanism for shifting the reversing mechanism of a rotor type sprinkler.
It is therefore the primary object of the present invention to provide a rotor type sprinkler with an improved over-center mechanism for shifting the reversing mechanism.
It is another object of the present invention to provide an over-center mechanism that is simpler and more reliable than conventional over-center mechanisms used in rotor type sprinklers.
It is still another object of the present invention to provide an improved over-center mechanism for shifting a reversing mechanism of a rotor type sprinkler having a horizontally disposed turbine and gear train reduction.
According to the present invention a sprinkler includes an outer housing having a lower end connectable to a source of pressurized water. A riser is vertically reciprocable along a vertical axis within the outer housing between extended and retracted positions when the source of pressurized water is turned ON and OFF. A nozzle is mounted at an upper end of the riser for rotation about the vertical axis. A turbine is mounted for rotation inside the riser. A drive mechanism is mounted within the riser and connects the turbine to the nozzle so that when the source of pressurized water is turned ON the resulting rotation of the turbine by the pressurized water will rotate the nozzle. The drive mechanism includes a reversing mechanism for causing the nozzle to rotate between a pair of arc limits. The reversing mechanism includes an over-center mechanism for shifting the reversing mechanism. The over-center mechanism includes a first lever and a second lever held together by a spring. The first lever and the second lever are pivotable relative to each other to shift the reversing mechanism.
Further, in accordance with the present invention, an over-center mechanism is provided for shifting a reversing mechanism of a rotor type sprinkler. The over-center mechanism includes a first lever, a second lever and a spring connected between the levers. The spring has a first end connected to the first lever at a first attachment point and a second end connected to the second lever at a second attachment point to hold the levers together in mating relation. The first and second levers are configured, and the spring attachment points are located, so that the levers will positively rotate between two predetermined opposite end limit configurations with minimal chance of stalling at a third configuration intermediate the two end limit configurations.